Economic difficulties

Some economists argue that a single world currency is unnecessary, because the U.S. dollar already provides many of the benefits of a world currency while avoiding some of the costs.[15]

If the world does not form an optimum currency area, then it would be economically inefficient for the world to share one currency.

A further argument is most easily conveyed by an analogy. Water carried in a biscuit baking pan will rapidly flow from high points to the lowest point, causing a sudden uncontrollable imbalance that forces the high points higher and the low point lower. The same quantity of water in cups on the biscuit pan will have no such inherent instability. Hegemonic currencies, free of regional limitations, flow rapidly away from high risk areas exacerbating their problems disproportionately to original causes[citation needed]. Such events are very damaging to the prosperity of the affected area. See for example the events leading up to, and subsequence consequences of, the Corralito in Argentina. For those with the power to do so, predicting, or even causing, such capital flights can lead to immensely profitable speculations; so profitable indeed that their likelihood of occurrence increases in proportion with the scale of the currency involved.